A control device, such as programmable logic controller (PLC), controls an FA system installed in a manufacturing site or similar sites in a production factory by executing an arithmetic operation in accordance with a control program. In such a control device, a suitable program can be installed to update an already installed program. In addition, in such a control device, a suitable program can be installed to add a function. Various techniques have been proposed so far for downloading a program into a control device. For example, Japanese Unexamined Patent Publication No. 2002-297388 (Patent Document 1) proposes a method for downloading only part of a system program.
In addition, for a control device, Japanese Unexamined Patent Publication No. 2009-223586 (Patent Document 2) discloses a technique for recording, into the control device, information on an error occurred in the control device.